In recent years, technologies related to adaptive cruise control (ACC) and chassis dynamometer (CDM) have been intensively developed. ACC is a technology that automatically adjusts vehicle speed to maintain a selected distance from a preceding vehicle. CDM is a machine used to warn a driver of potential collision and operate a brake accordingly. A vehicle with ACC and CDM uses forward-looking radar to detect a preceding vehicle. Typically, the front surface of the radar is covered by a radar cover in order to protect the radar from surrounding environments including moisture. The radar cover oftentimes poses a problem. For example, it can cause the radar to lose a signal by blocking the radar wave. This problem becomes serious, in particular, when a loss is caused by reflection of the radar wave due to the thickness of the radar cover.
A prior art technology was proposed to solve this problem by optimizing the thickness of the radar cover so as not to cause such refraction. More particularly, in the proposed technology, the tilt of the front surface of the cover and the wavelength of the radar wave are used to calculate an optimum thickness of the cover.
calculated for a normal weather condition. That is, it is calculated by using a dielectric constant of the air which is for the weather condition where it does not rain. However, the equivalent dielectric constant of the air changes by snow, fog, rain, and the like, since the refractive index of the radar wave changes. The radar thus does not perform well in the event of weather changes.
There is thus a need for a new technology that can solve the problems associated with the prior art technology.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.